Fig. 2. Dimerization of ADAR protein. (A) Yeast (L40) was cotransformed with plasmids encoding the full-length Adar fused to the LexA binding domain in the yeast expression vector pBTMK or fused to the DNA activation domain of GAL4 in the pACT2 vector. Positive protein–protein interactions were detected as blue colonies after a β-galactosidase assay. Full-length ADAR forms homodimers, and no interaction was detected with just the deaminase domain (DM) or with the controls. The positive control (C+) is the interaction between PAB1-2 and Paip 1, and the negative control (C-) is the absence of interaction between PAB1-2 and IRP (Gray et al., 2000). (B) The ADAR 3a isoform with epitope tags (c-Myc or HA) was transcribed and translated in vitro. The 3/4 isoform was generated with the anti-c-Myc epitope tag. The proteins were mixed and then co-immunoprecipitated with Myc monoclonal antibody. The immunoprecipitated proteins were electrophoresed on 8% SDS–polyacrylamide gel and revealed with an anti-HA polyclonal antibody. Recombinant ADAR 3a is able to form both homodimers and heterodimers.